2006 CurrentScience KashmirEQ DCR CVRM

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SCIENTIFIC CORRESPONDENCE

CURRENT SCIENCE, VOL. 90, NO. 8, 25 APRIL 20061066

control larvae excreted faeces as loose

particles without membranous structure

(Figure 3). Microscopic examination re-

vealed that the non-cellular membranous

structure was suspected to be the peritropic

membrane (PM). It has been documentedthat the root extract of Derris affects

peritropic matrix structure of A. aegypti13.

It has been recognized that the PM sepa-

rates food from epithelial cells of the gut

involved in digestion and absorption of

nutrients from the gut lumen, and acts as

a protective barrier against various chemical,

physical and microbial food components14.

It may be argued from our results that

the C. inerme powder taken by the larvae

along with other food materials caused

damage to the PM and subsequently affected

the process of digestion and absorption.

Disruption of growth of the larvae to pupaeobserved in this study may be the result

of disturbances in the digestive process,

which led to inadequate supply of nutri-

tion to the larvae.

1. Green, M. M., Singer, J. M., Sutherland,

D. J. and Hibben, C. R., J. Am. Mosq.

Control Assoc., 1991, 2, 282–286.

2. Sukumar, K., Perich, M. J. and Boobar,

L. R., J. Am. Mosq. Control Assoc., 1991,

7, 210–237.

3. Perich, M. J., Carl, W., Wolf-gang, B.

and Tredway, K. E., J. Med. Entomol.,

1994, 31, 833–837.

4. Pathak, N., Mittal, P. K., Singh, O. P.,

Vidyasagar, D. and Vasudevan, P., Insect

Pest Control , 2000, 46, 53–55.

5. Patterson, B. D., Wahba Khalh, S. K.,

Schermeister, L. J. and Quraishi, M. S.,

Lloydia, 1975, 391–403.

6. Mittal, P. K., Adak, T. and Sharma, V.

P., Pestic. Res. J ., 1995, 7, 35.

7. Mulla, M. S. and Su, T., J. Am. Mosq.

Control Assoc., 1999, 15, 133.

8. Aliero, B. L., Afr. J. Biotechnol., 2003,2, 325–327.

9. Zebitz, C. P. W., Entomol. Exp. Appl.,

1984, 35, 11–16.

10. Kalyanasundaram, M. and Das, P. K.,

Indian J. Med. Res., 1985, 82, 19–23.

11. Finney, D. J., Probit Analysis, Cambridge

University Press, Cambridge, 1971, III edn.

12. Pereira, J. and Gurudutt, K. N., J. Chem.

Ecol ., 1990, 16, 2297–2306.

13. Gusmao, D. S., Pasco, V., Mathias, L.,

Vieira, I. J. C., Braz-Filho, R. and Lemos,

F. J. A., Mem. Inst. Oswal. Do. Cruz .,2002, 97, 371–375.

14. Peters, W., Zoophysiology , Springer-

Verlag, Berlin, 1992, vol. 30, p. 238.

ACKNOWLEDGEMENT. Financial assistance

provided by UGC, New Delhi is acknowledged.

Received 15 February 2005; revised accepted

10 December 2005

P. B. PATIL

S. N. HOLIHOSUR *

V. L. K ALLAPUR

Department of Zoology, Karnatak University,

Dharwad 580 003, India

*For correspondence.

e-mail: [email protected]

Effects of the 2005 Muzaffarabad (Kashmir) earthquake on built

environment

Studying the effects of earthquakes has

long been recognized as a necessary step

to understand the natural hazard and its

risk to the society in the long term. A

rapid assessment of general damage survey

and documentation of initial important

observations, not only help management

of emergency response and rehabilitation

activities, but also help to assess the need

of follow-up areas of research1,2. The

Muzaffarabad earthquake of 8 October

2005 which caused major devastation on

both sides of the Line of Control (LoC)in Kashmir, presented another opportunity

to further our understanding of earthquake

risk in the region.

The Mw 7.6 earthquake on 8 October

2005 was a major earthquake at a depth

of 26 km from the surface with its epi-

centre located at 34.493° N, 73.629°E,

19 km northeast from Muzaffarabad, the

capital town of the Pakistan Occupied

Kashmir (POK) and 170 km west-north-

west of Srinagar, Jammu & Kashmir, India

(USGS). The event which was similar in

magnitude to the 2001 Gujarat earthquakeand the 1935 Quetta earthquake caused

widespread destruction in POK, Paki-

stan’s North-West Frontier Province

(NWFP), and western and southern parts

of the Kashmir on the Indian side of

LoC. This earthquake is associated with

the known subduction zone of active

thrust fault along the Himalayan moun-

tain ranges in the area where the Eurasian

and Indian tectonic plates are colliding

and moving northward at a rate of 40 mm/yr

(Figure 1).

The worst affected major towns on the

Indian side of LoC are Tangadhar in Kup-wara district and Uri in Baramulla dis-

trict. Significant damages have also been

reported from the Poonch and Rajouri

district further south from the epicentre

on the Indian side of LoC. During the re-

connaissance survey we visited places

along National Highway NH1A during

14–19 October 2005 from Srinagar to Uri

and along Sopore, Durgwilla, Kupwara,

Traigaon on the road to Tangdhar.

Damage to buildings and other struc-

tures in general agreed well with the in-

tensity of ground shaking observed atvarious places, with the maximum of

VIII at Uri, VII at Baramulla and Kupwara

and V at Srinagar on MSK scale3. How-

ever, the collapse of stone walls of random

rubble types was a surprise even with

much lesser shaking. It has been well es-

tablished that the local soil site and to-

pographical conditions play a significant

role in modifying the nature of ground

motion which leads to varying degree of

response to similar structures. Structures

located on ridges and along steep slopes

were subjected to a greater degree of

damage in comparison to those located invalleys, during this earthquake as well.

The affected region lies in the top two

high risk seismic zones of IV and V of

Indian seismic code IS:1893 (ref. 4) with

an expected intensity of IX or more in

the zone V and of VIII in the zone IV.

The region affected by the Muzaffara-

bad earthquake is mountainous terrain

where the settlement is dense in valleys

and sparse on hill slopes. Major civil en-

gineering projects in the area are high-

ways, bridges, small dams and micro

hydro-electric projects and a few RC framed buildings. The housing units are largely


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CURRENT SCIENCE, VOL. 90, NO. 8, 25 APRIL 2006 1067

low rise brick and stone masonry load

bearing types often in association with

timber. The diaphragms vary from pitched

flexible roofs to mixed flexible and rigid

concrete floors and roofs.

Structures need to have suitable earth-quake-resistant features to safely resist

large lateral forces that are imposed on

them during infrequent earthquakes. Or-

dinary structures for houses are usually

built to safely carry their own weight and

low lateral loads caused by wind and

therefore, perform poorly under large

lateral forces caused by even moderate

size earthquakes.

The majority of buildings in the affected

region use the unreinforced masonry

walls as bearing and enclosure walls.

These masonry structures can be viewed

as box-type structures in which the pri-

mary lateral resistance against the earth-

quake forces is provided by the membrane

action of the diaphragms (floors and

roofs) and bearing walls. The seismic

performance of load-bearing masonry

structures depends heavily on the struc-tural characteristics (strength, stiffness

and ductility) of surrounding walls to resist

in-plane and out-of-plane inertia forces

and of the diaphragms (floors and roofs)

to not only safely resist the shear forces

but also to distribute the forces to verti-

cal elements (walls) and maintain the in-

tegrity of the structure.

In Kashmir, traditional timber–brick

masonry construction consists of burnt

clay bricks filled in a framework of tim-

ber to create a patchwork of masonry,

which is confined in small panels by the

surrounding timber elements. The result-

ing masonry is quite different from typi-

cal brick masonry and their performance

in this earthquake has been once again

shown to be superior with no or very lit-

tle damage. No collapse was observed in

such masonry even in the areas of highershaking. This timber-lacing of masonry,

which is locally referred as dhajji-dewari

(meaning patch quilt wall) has excellent

earthquake-resistant features. Presence of

timber studs, which subdivides the infill,

arrests the loss of the portion or all of

several masonry panels and resisted pro-

gressive destruction of the rest of the

wall (Figure 2). Moreover, the closely

spaced studs prevent propagation of di-

agonal shear cracks within any single

panel, and reduce the possibility of out-

of-plane failure of masonry of thin half-

brick walls even in higher stories and gable portion of the walls. Dhajji-dewari

system is often used for walls of upper

stories, especially for the gable portion

of the wall, even when the walls in bot-

tom stories could be made of brick or

stone masonry (Figure 2 a).

In older constructions, another form of

timber-laced masonry, known as Taq has

been practiced in which large pieces of

wood have been used as horizontal run-

ners embedded in the heavy masonry

walls, which add to the lateral load re-

sisting ability of the structure (Figure2 b). The concept of Dhajji-dewari has

also been extended to develop a mixed

construction in which stones are used as

filler hard material in wall panels created

by a series of piers in softer coursed brick

masonry of greater integrity under lateral

loads (Figure 2 c). The masonry walls

with stones confined in such a manner

have performed quite satisfactorily, in

contrast to usual brick or stone masonry.

In the upper reaches of North Kashmir

Himalayas, majority of houses use stone

masonry in mud mortar for walls and

flexible diaphragms for floors and roofsconsisting of timber. Stone masonry is

produced from a wide range of materials

and constructed in many different forms

that have shown varying degree of per-

formance in this earthquake. Unreinforced

stone masonry is very durable even in the

hostile environment and can accommo-

date movements and resist natural forces

without becoming unstable and falling

apart, especially when they are laid in

even courses after proper dressing (Fig-

ure 3).

However, some forms of stone masonry,especially Random Rubble (R/R) stoneFigure 1. Location of epicentre of the earthquake and its aftershocks, Main Central Thrustfault, and the towns visited in the Indian side of Line of Control (LoC).


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Figure 2. Traditional masonry for proven earthquake resistance. a , Dhajji -dewari system of timber laced masonry for confining masonry in small panels; b , Taq system of embedding timber thick walls; c , Brick masonry piers for timbers in stone infilled wall.

Figure 3. Examples of mixed construction involving dhajji-dewari and dressed/undressed stone masonry and brick masonry.

Figure 4. Out-of-plane collapse of stone masonry walls.

masonry construction are extremely vul-

nerable to earthquakes. Undressed stones

are laid in mud or cement mortar and

plastered in cement mortar to provide

finished surface. Most of government buildings, hospitals, schools, jails, etc.,

built during the last 4 to 5 decades suf-

fered heavy damage especially when the

structure is old. This was primarily due

to the fact that the walls could not main-

tain their integrity during the shaking.The collapsed walls of army buildings in

Uri and Kupwara are a few examples.

Such out-of-plane failures arising from

the dynamic instability of unsupported

walls were also evident in collapsed tall

slender end wall in brick masonry as well.Moreover, masonry walls are weakened

a b c

a

b

a b c


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CURRENT SCIENCE, VOL. 90, NO. 8, 25 APRIL 2006 1069

by openings for doors and windows (Fig-

ure 4).

Deficiencies of stone masonry walls

were more evident in R/R type masonry

and were responsible for the majority of

the observed damage in the earthquake-affected areas. Such deficiencies can

render typical brick masonry buildings

vulnerable to damage as shown in Figure

5. However, timber-laced masonry can

maintain its integrity even when the sup-

porting masonry walls in lower stories

are severely damaged (Figure 6).

Pitched roofs have been the most popu-

lar choice as a roofing system for build-

Figure 5. Damage to brick masonry build-ings. a , Out-of-plane collapse of walls; b , In- plane failure of masonry walls in lower storiesand out-of-plane collapse at uppermost storey.

Figure 6. Timber-laced masonry in gablewall suffered little damage whereas extensive

damage in stone masonry wall rendered the building unsafe at Uri.

ings. However, there are many variants

of pitched roofs with varying degree of

seismic performance. In rural areas and

low cost houses, roofs are either com-

posed of wooden joists and planks or

simple wooden trusses and rafters. Ingovernment buildings, wooden planks

are placed on rafters to support the roof-

Figure 7. Failure of supporting walls for theroof in a traditional building using Taq systemof masonry at Baramulla.

Figure 8. Simply supported prestressed con-crete girder bridge on NH1A in Zone V whichlacks restrainers for preventing unseating dur-ing earthquakes.

Figure 9. Landslide on NH1A near Uri dis-rupted the road traffic.

ing material. Corrugated Galvanized Iron

(CGI) sheets have also been used as a

roofing material in many cheaply built

school buildings. These roofs are inher-

ently weak in shear and cannot tie the

walls together even when they are prop-erly connected to them. Most of roof

failures can be attributed to a combination

of deficiencies such as loss of support of

roof trusses and rafters due to failure of

masonry walls and failure of roof truss

itself due to failure of joints and/or

members forming the truss or other roof

supporting structure (Figure 7).

The area has a number of highways and

pedestrian bridges over rivers, rivulets,

and gorges. No serious damage to any of

the highway bridges was noticed in the

areas visited away from the epicenter.

However, it has been reported that theAman Setu at India-Pak border closer to

the epicenter has suffered damage. Most

of pedestrian bridges were of suspension

types and no particular damage to the

bridge structure or to the supporting py-

lons was noticed. The affected region

which may experience ground shaking

more than IX on MSK scale, has a num-

ber of major bridges which are simply

supported prestressed concrete girder

type with inadequate seating or no provi-

sion to prevent unseating (Figure 8).

Roads closer to epicentral area in themountainous region suffered extensive

landslides which resulted in the closure

of traffic for many days (Figure 9). The

road to Tangadhar from Kupwara was

not open even a week after the quake.

Fissures on roads were noticed at places

which were primarily due to ground

movement across unstable slopes. Pipe-

lines for drinking water supply broke at

several places causing severe hardships.

An overhead water tank on shaft supported

staging in Traigaon suffered circumfer-

ential flexure tension and shear cracking

which was empty at the time of earth-quake (Figure 10). Such damages have

been observed in many past earthquakes

which highlight the inadequacy of current

design methods of such tanks.

The damage to built environment, eco-

nomic loss and human casualties caused

by Himalayan earthquakes are increasing

rather proportionally with the growth of

settlements and population in its upper

reaches. Significant damage to residential,

community and government buildings

result from prevailing stone masonry

buildings, especially those with random-rubble types, which are well known for

a

b


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poor seismic performance. Buildings should

not only meet the functional requirementsof occupants but also essential require-

ments for sound earthquake-resistant de-

sign and construction.

Most residential units in the affected

area relied on load-bearing masonry

walls for seismic resistance. Much of the

damage could be attributed to inferior

construction materials, inadequate sup-

port of the roof and roof trusses, poor

wall-to-wall connections, poor detailing

work, weak in-plane wall due to large

openings, out-of-plane instability of

walls, lack of integrity or robustness,

asymmetric floor plans and ageing. Con-ventional unreinforced masonry laced

with timber performed satisfactorily as

expected as it arrests destructive crack-

ing, evenly distributes the deformation

which adds to energy dissipation capac-

ity of the system, without jeopardizing

its structural integrity and vertical load

carrying capacity. There is an urgent

need to revive these traditional masonry practices which have proven their ability

to resist earthquake loads, in contrast to

contemporary colonial-style masonry

buildings. The seismic performance of

such masonry systems should be resear-

ched and guidelines developed for their

cost-effective implementation which can

optimally exploit their inherent ability to

resist seismic actions.

Modern bridges, roads, water tanks,

etc., which have been constructed in the

Kashmir region without due considera-

tion of high seismic activities of the Hi-

malayan region making such civilinfrastructure extremely vulnerable for

future earthquakes. There is an urgent

need that prevailing standard codes of

practices for earthquake-resistant design

and construction should be adhered to,

and wherever these provisions are defi-

cient, detailed studies should be under-

taken to evaluate and improve them.

Similarly, seismically deficient structures

need to be strengthened to reduce their

vulnerability.

1. Post-Earthquake Investigation Field Guide:

Learning from Earthquakes, Earthquake

Engineering Research Institute, Oakland,

CA, 1996, Publication No. 96-1, p. 144.

2. Reducing Earthquake Hazards: Lessons

Learned from Earthquakes, Earthquake

Engineering Research Institute, Oakland,

CA, 1986.

3. EERI News Lett ., Dec. 2005.

4. Indian Standard Criteria for Earthquake

Resistant Design of Structures: Part 1–

General Provisions and Buildings, Bureau

of Indian Standards, New Delhi, 2002,

IS:1893 (Part 1).

ACKNOWLEDGEMENTS. We thank the

numerous officers and staff of IRCON Inter-

national and Military Engineering Services

(MES) in the affected area who provided help

and support during the field visit. Special

thanks are due to Professor Sudhir K. Jain, IIT

Kanpur, for encouragement and support in

carrying out the reconnaissance studies in one

of the most difficult areas of the country. We

thank DST for financial support.

Received 24 October 2005; revised accepted

17 February 2006

DURGESH C. R AI*C. V. R. MURTY

Department of Civil Engineering,

Indian Institute of Technology,

Kanpur 208 016, India

*For correspondence.

e-mail: [email protected]

Reassessment of earthquake hazard in the Himalaya and implicationsfrom the 2004 Sumatra–Andaman earthquake

In earlier accounts of seismicity and long-

term forcasting of earthquakes, three

great earthquakes with magnitude ≥8,

namely 1905 Kangra, 1934 Bihar–Nepal

and 1950 eastern Assam in Himalaya and

a fourth one, i.e. 1897 western Assam

with magnitude Mw 8.0 were recogni-

zed1–3 (Figure 1). Regions between the

rupture zones of these earthquakes were

recognized as seismic gaps

4

, which wereinterpreted to have accumulated potential

slip for generating future great earth-

quakes4,5. In recent years re-examination

of old recorded data has led to revision

of the magnitudes and rupture zones of

these earlier classified great earthquakes6,7,

with new information being extracted

from the archives for calculating magni-

tudes of historical earthquakes: 1505,

1803, 1833 and others8. GPS9 and palaeo-

seismological studies

10

have added an-other dimension to our understanding of

the kinematics of seismogenic faults and

seismotectonics.

The great Kangra earthquake of 4

April 1905 was assigned magnitude 8.1

with its rupture zone extending ~300 km

from Kangra to Dehra Dun1,11. This

magnitude has been recently revised to

Mw 7.8 with rupture extending 90 km

along the strike7; the intensity VIII esti-

mated at Dehra Dun is interpreted as aseparate triggered event. The epicentre of

Figure 10. A 50000 gallon water tank at Traigaon developed flexure tension cracks in its supporting shaft rendering it unsafe for use.

2006 CurrentScience KashmirEQ DCR CVRM

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